Impacts of Melt Spinning and Element Replacement on the Electrochemical Performances of the RE–Mg–Ni-Based A₂B₇-Type Electrode Alloys

Abstract:

The RE–Mg–Ni-based A₂B₇-type La_0.75−xPr_xMg_0.25Ni_3.2Co_0.2Al_0.1 (x = 0, 0.1, 0.2, 0.3, 0.4) electrode alloys fabricated by melt spinning technology. The impacts of the melt spinning and the replacement of La by Pr on the microstructures and electrochemical performances of the alloys were systematically investigated. The results indicate that the as-cast and spun alloys hold a compound phase structure, containing (La, Mg)₂Ni₇ and LaNi₅ phases as well as a residual phase LaNi₂. A notable grain refinement of the alloys without altering the phase structures of the alloys obtained by melt spinning. The discharge capacity of the alloy (x = 0.2) tend to first augments and then falls with the growing spinning rate. And the as-spun (10 m/s) alloy gains the maximum discharge capacity as Pr content augmenting in the alloys. Furthermore, the measurements of the electrochemical hydrogen storage kinetics reveal that the high rate discharge ability (HRD), the hydrogen diffusion coefficient (D) and the limiting current density (IL_{Subscript text}) of the alloys first increase then decrease with the rising of the spinning rate and the amount of Pr substitution.

• Periodical: Advanced Materials Research (Volume 629)
• Pages: 3-8
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.629.3
• Online since: December 2012
• Authors: Yang Huan Zhang, Le Le Chen, Tai Yang, Hong Wei Shang, Li Сui Chen, Dong Liang Zhao
• Keywords: A₂B₇-Type Alloy, Electrochemical Characteristics, Melt-Spinning, Replacing La by Pr

References

[1] Kadir K, Sakai T, Uehara I. Synthesis and structure determination of a new series of hydrogen storage alloys; RMg2Ni9 (R=La, Ce, Pr, Nd, Sm and Gd) built from MgNi2 Laves-type layers alternating with AB5 layers. J Alloys Compd 1997; 257: 115–21.

DOI: 10.1016/s0925-8388(96)03132-5

[2] Kohno T, Yoshida H, Kawashima F, Inaba T, Sakai I, Yamamoto M et al. Hydrogen storage properties of new ternary system alloys: La2MgNi9, La5Mg2Ni23, La3MgNi14. J Alloys Compd 2000; 311: L5–7.

DOI: 10.1016/s0925-8388(00)01119-1

[3] Liu YF, Cao YH, Huang L, Gao MX, Pan HG. Rare earth–Mg–Ni-based hydrogen storage alloys as negative electrode materials for Ni/MH batteries. J Alloys Compd 2011; 509: 675–86.

DOI: 10.1016/j.jallcom.2010.08.157

[4] Zhang YH, Li BW, Ren HP, Guo SH, Qi Y, Wang XL. Structures and electrochemical hydrogen storage characteristics of La0. 75−xPrxMg0. 25Ni3. 2Co0. 2Al0. 1 (x = 0–0. 4) alloys prepared by melt spinning. J Alloys Compd 2009; 485: 333–9.

DOI: 10.1016/j.jallcom.2009.05.094

[5] Zhang YH, Li BW, Ren HP, Guo SH, Qi Y, Wang XL. Structures and electrochemical cycle stability of La0. 75−xPrxMg0. 25Ni3. 2Co0. 2Al0. 1 (x = 0–0. 4) alloys prepared by melt spinning. Mater Chem Phys 2009; 118: 129–34.

DOI: 10.1016/j.matchemphys.2009.07.016

[6] Zhang YH, Ren HP, Li BW, Guo SH, Wang QC, Wang XL. Structures and electrochemical hydrogen storage behaviours of La0. 75−xPrxMg0. 25Ni3. 2Co0. 2Al0. 1 (x = 0–0. 4) alloys prepared by melt spinning. Int J Hydrogen Energy 2009; 34: 6335–42.

DOI: 10.1016/j.ijhydene.2009.06.007

[7] Gasiorowski A, Iwasieczko W, Skoryna D, Drulis H, Jurczyk M. Hydriding properties of nanocrystalline Mg2−xMxNi alloys synthesized by mechanical alloying (M=Mn, Al). J Alloys Compd 2004; 364: 283–41.

DOI: 10.1016/s0925-8388(03)00544-9

[8] Zheng G, Popov BN, White RE. Electrochemical determination of the diffusion coefficient of hydrogen through an LaNi4. 25Al0. 75 electrode in alkaline aqueous solution. J Electrochem Soc 1995; 142: 2695–8.

DOI: 10.1149/1.2050076